This invention is directed to a bag gripper for use in conjunction with a form, fill and seal bagging machine. The bag gripper assists during the sealing of a bag which is formed, filled, and sealed on this type of machine.
In the packaging industry the word "seal" is used for both hardware which forms "seals" or joints and also for the "seal" or joint itself. Thus, side seals (hardware) form side seals (joints) between films. In using the words "seal" or "seals" in this specification, if its meaning is not clear from the context of the sentence it is used in, it will be more fully identified by modifiers or synonyms.
Thus, for certain specific hardware, the word "bar" will be used to indicate that it is the hardware element which is being identified. Unless otherwise indicated or modified, the word "seal" by itself will generally refer to the joint which is formed. "Side seal", "top seal", "bottom seal" and "cross seal" or "transverse seal" unless other wise indicated or modified will refer to joints between the film whereas "head seal" will always refer to specific hardware to form the cross or transverse seal.
With the advent and growth of certain industries, most particularly the fast food industry, machines have been developed which continuously form, fill and seal bags or pouches. These machines utilize continuous rolls of heat sealable film which are heat sealed together to form bags or pouches. Typically side seals (side joints) are continuously made between the front and back film, a bottom seal (bottom joint) is made, the bag or pouch filled and the bag or pouch completed by forming a top seal (top joint).
Most of the form, fill and seal bagging machines presently utilized, are utilized for convenience foods and/or packaging of food condiments. Typically a gang of side seals, i.e. the hardware that forms the side seals, will be lined up in parallel across the width of the continuous front and back films. These form individual parallel side seals or side joints which are spaced apart from each other at varying widths of from approximately 11/2 inches, which would be utilized for condiment packaging, upwards to approximately 12 inches, which would be utilized for food or other type items. Typically the rolls of film utilized for the front and back surfaces will be approximately 12 to 24 inches in width and as such simultaneously anywhere from several to approximately a dozen or so bags or pouches can be concurrently formed, filled and sealed by the machine.
As the continuous front and back films move through the machine, at least two or more side seals (joints) are formed between these films. This forms the side edges of parallel bags. These side seals (joints) are then cut or severed to separate the individual parallel bags. A cross or transverse seal (joint) is then made across the width of the film. This seal is normally made much wider than the side seals and is split such that concurrently a top seal will be made for the bottom most of two adjoining or adjacent pouches and a bottom seal will be made for the top most of the two adjoining or adjacent pouches. When the bottom seal of a pouch, whether it is a single pouch or a gang of side by side pouches, is formed the pouch is then filled with product utilizing filling tubes, filling heads or the like and then the pouch with the product inside of it is completed by forming the cross seal which seals the top of a filled bag and creates the bottom seal for the next empty bag which will be filled.
The cross or transverse seal is generally made utilizing a sealing hardware component called a head seal. This forms a seal (joint) which is wide enough to serve as both a top seal for one package and a bottom seal for another package. This head seal can include a cut off knife fixed to it or independent cut off mechanism can be located below the head seal to sever the cross seal to form individual top seals and bottom seals on the adjacent bags or pouches.
The head seal as well as the side seals (hardware) are generally formed of metallic elements, i.e. sealing bars, which include resistance heaters therein which heat the metallic bars. A back and a front heated sealing bar are brought together squeezing the film between them to heat seal the front film and the back film together forming an impervious seal between the two films. Advancement of the film, operation of the side seals (hardware) and the head seal is all capable of being controlled by microprocessors and the like such that the form, fill and seal bagging machines are capable of essentially continuous operation. Operator attention is only necessary for loading the rolls of continuous heat sealing film and loading the supply of the component product which is being sealed in the bags or pouches.
In forming, filling and sealing small bags or pouches such as condiment pouches or small food or other product pouches or bags, the amount of the component which is added to the partly formed empty bag or pouch is generally small compared to the flex strength of the film being utilized to form the bag or pouch. Additionally, the distance between the respective left and right side seals of each individual pouch or bag is also small. In view of this after filling but before the top seal is formed these pouches or bags are fairly stable and do not tend to balloon out to an significant extent under the weight of the contents. Unless there are wrinkles from other sources, the head seal then smoothly joins the front film and the back film together to form a smooth and continuous cross seal.
However the size of the bags or pouches and the materials which could be located therein has generally been limited by the inability to control ballooning of larger bags after they are filled but prior to forming the cross seal to seal the top of the bag or pouch. This generally limited what materails and what volume and weight of these materials could be appropriately packaged utilizing this packaging technique. Once sizes of approximately one quarter pound of liquid volume are encountered, the weight of the liquid in the filled but not as yet top sealed bag tends to balloon out the front and back film surfaces separating these surfaces from one another. As a result, the bag is distorted and assumes somewhat of a tear drop shape as it is suspended on the form, fill and seal bagging machine. When so shaped it is potentially possible when the front and back sufaces are contacted by the head seals and brought together that a wrinkle or a crimp can develop in one of the front or back films. This can then form an incomplete seal within the cross seal between two adjacent bags and when the bags are separated, one or both will leak.
Because of the tendency of larger bags or bags filled with heavy liquids to bulge, balloon or otherwise distort in between the filling step and formation of the cross seal, heretofore this has limited form, fill and seal bagging machines as to the size of bags or pouches which could be formed or the material which could be packaged therein.